Since the advent of the video cassette recorder (VCR), viewers of transmitted video and audio programming have been able to privately record their favorite programs. As a result, such technology has allowed the viewer to “time-shift” television programs of interest to a subsequent, more convenient time. More recently, digital video recorder (DVR) units, often provided in satellite and cable television receivers, or “set-top boxes,” have supplied the viewer a more convenient means of time-shifting audio/video streams by allowing a larger number of programs to be recorded in a more automated fashion without the use of removable storage media.
Given this time-shifting capability and the amount of data storage available in such devices, users often do not view a recorded program or other audio/video stream until several days, or even weeks, after the stream was first recorded. As a result, some information provided in the audio/video stream, such as the subject matter of the program of interest, or even the informational content of a commercial, may be outdated by the time the user finally views the recorded stream.